He then warned her, "Oh, from One Direction? Keep away from him. He's pure. OK?"

While Lovato seemed both amused and offended by his response, she reassured Cowell that right now she's not looking for a boyfriend. "I'm not looking for anything. I'm not going to date anybody for a whole year," she said, but implied that the two had discussed something romantic when she added, "And I made that clear to him."

Cowell, not completely buying it, then asked, "Have you kissed him?"

That question left Demi a bit smiley, but still she still assured him nothing has happened between them. "No. Simon, no," she told him. "Oh my gosh!" she muttered walking away from him.

The conversation and buzz around Niall and Demi hasn't died down all summer, even though she has consistently insisted they're just friends. "There is nothing going on. Niall's my friend," she said earlier this week, while doing press for the show. "I'm really happy for One Direction and the success that they've had. It just goes to show you how crazy this competition is to making stars and the success that they have. He's a good friend of mine."

The boys of One Direction got their start on the U.K. version of the show in 2010. And, they even made a pre-taped appearance on Wednesday's premiere in which they welcomed both Lovato and fellow newbie Britney Spears to the "X Factor" family.

What did you think of the season two premiere of "X Factor"? Leave your comment below!